Table 1. The basic characteristics of studies in meta-analysis.
| First author | Publication year | Region | Year of admitted patients | Case number | Male number | Quality rating | ||
|---|---|---|---|---|---|---|---|---|
| Total | Mild | Severe | ||||||
| Chen et al. [18] | 2015 | East, China | 2013–2014 | 263 | 142 | 121 | 137 | Fair |
| Chen et al. [19] | 2013 | East, China | 2012 | 126 | 64 | 62 | 80 | Fair |
| Chong et al. [20] | 2003 | Singapore | 2000–2001 | 138 | NA | NA | 81 | Good |
| Deng et al. [21] | 2016 | West, China | 2014–2015 | 216 | 88 | 128 | 133 | Fair |
| Han et al. [22] | 2016 | East, China | 2013–2015 | 300 | 150 | 150 | 174 | Fair |
| Han et al. [23] | 2014 | China | 2008–2010 | 91 | 32 | 59 | 55 | Good |
| Han et al. [24] | 2011 | East, China | 2009 | 102 | 77 | 25 | 62 | Good |
| He et al. [25] | 2019 | East, China | 2012–2014 | 132 | 57 | 75 | 87 | Fair |
| Huang et al. [26] | 2012 | East, China | 2011 | 56 | 45 | 11 | 36 | Fair |
| Jiang et al. [27] | 2013 | Central, China | 2011 | 89 | 55 | 34 | NA | Fair |
| Jiang et al. [28] | 2012 | East, China | 2010 | 573 | 77 | 496 | 375 | Fair |
| Li et al. [29] | 2014 | Central, China | 2012 | 503 | 423 | 80 | 287 | Good |
| Li et al. [30] | 2014 | East, China | 2012 | 571 | 221 | 350 | 351 | Good |
| Li et al. [31] | 2013 | West, China | 2011 | 318 | 202 | 116 | 211 | Good |
| Liu et al. [32] | 2013 | East, China | 2009–2011 | 164 | NA | 123 | 130 | Good |
| Long et al. [33] | 2016 | Central, China | 2011–2014 | 553 | NA | NA | 335 | Fair |
| Pan et al. [34] | 2012 | Central, China | 2008–2009 | 369 | 140 | 229 | 241 | Good |
| Pan et al. [35] | 2019 | West, China | 2017–2018 | 55 | 17 | 38 | 38 | Fair |
| Qiu et al. [36] | 2019 | Central, China | 2013–2017 | 7203 | NA | NA | 4580 | Good |
| Ren et al. [37] | 2016 | East, China | 2015 | 86 | 19 | 67 | 52 | Good |
| Song et al. [38] | 2014 | Central, China | 2010–2012 | 167 | NA | NA | 107 | Good |
| Tang et al. [39] | 2011 | East, China | 2008–2009 | 186 | 62 | 124 | 120 | Good |
| Wang et al. [40] | 2014 | Central, China | 2009 | 120 | 60 | 60 | 72 | Fair |
| Wang et al. [41] | 2020 | West, China | 2013–2018 | 459 | NA | NA | 295 | Good |
| Xu et al. [42] | 2011 | Central, China | 2010 | 315 | NA | 210 | 210 | Good |
| Yang et al. [43] | 2020 | East, China | 2017 | 261 | 206 | 55 | 174 | Good |
| Zhang et al. [44] | 2017 | East, China | 2009–2014 | 530 | 345 | 185 | 379 | Good |
| Zhang et al. [45] | 2011 | China | 2008–2009 | 765220 | NA | 4067 | NA | Fair |
| Zhang et al. [46] | 2016 | Central, China | 2014–2015 | 100 | 58 | 42 | 64 | Good |
| Zheng et al. [47] | 2017 | West, China | 2009–2016 | 179 | NA | 52 | 112 | Good |
| Zheng et al. [48] | 2017 | East, China | 2014–2015 | 82 | 30 | 52 | 44 | Good |
| Zhou et al. [49] | 2012 | Northeast, China | 2008–2011 | 2379 | 1798 | 581 | 1385 | Good |
NA: not applicable